A connection device switching from a pre-use state in which a syringe and a vial are spaced from each other and the double-head cannula does not penetrate lid members of the syringe and the vial, to a use state in which the syringe and the vial are brought close to each other and the double-head cannula penetrates the lid members of the syringe and the vial to establish communication between internal spaces of the syringe and the vial is conventionally known.
As such a connection device, a connection device in which the syringe and the vial are connected to both ends of cylindrical holding means and the double-head cannula is provided inside the holding means to be movable (PTL 1).
According to the connection device, by bringing the syringe close to the vial held by the holding means, the double-head cannula can penetrate lid members of the syringe and the vial to establish communication between internal spaces thereof.